本文以硝态氮(NO₃⁺-N)作为唯一氮形态的模拟污水，以浮水植物大薸为受试材料，研究了大薸对硝态氮的去除效果以及生长参数、硝酸还原酶、抗氧化酶活性和可溶性糖等的生理响应变化。结果表明，随外源硝态氮浓度的增加，培养液中硝态氮的减少量也越多。与对照值相比，施加硝态氮对大薸的硝酸还原酶活性产生明显的抑制作用，最多可达约44%。硝态氮对大薸的生长没有产生明显影响，处理组的叶绿素含量、可溶性蛋白和可溶性糖含量都高于对照组。NO₃⁺-N激活了大薸体内的抗氧化酶活性，比如SOD，CAT和POD (LN和MN)。总体来说，可溶性糖含量上升和抗氧化酶激活支持它们有效参与、改善大薸对NO₃⁺-N的耐性。
In this study, the eliminate capacity for nitrate nitrogen (NO₃⁺-N) and the effects of nitrate-nitrogen on growth index, nitrate reductase and antioxidant enzyme activities, and soluble sugar were investigated in Pistia stratiotes growing in simulated wastewater using NO₃⁺-N as the sole nitrogen form. The results indicated that the loss of NO₃⁺-N increased significantly with augment of exogenous NO₃⁺-N in cultural solution. Compared to the control value, plants supplied with NO₃⁺-N had decreased nitrate reductase activity with the maximum reduction of 44%. The NO₃⁺-N had less influence on growth of P. stratiotes. Pigment, soluble protein and soluble sugar content was significantly higher (P < 0.01) in NO₃⁺-N treated P. stratiotes respectively, compared to controls. The activation of antioxidant enzymes, such as superoxide dismutase and catalase, peroxidase (LN and MN) was observed in NO₃⁺-N exposed P. stratiotes. Overall, the increase in concentration of soluble sugar and activation of antioxidative enzymes support their effective involvement in improving NO₃⁺-N tolerancein P. stratiotes.